Fibroblast growth factor receptor substrate 2 is a protein that in humans is encoded by the FRS2 gene. FRS2 is overexpressed and amplified in several cancer types, including prostate cancer. FRS2 is an adapter protein that links activated FGR and NGF receptors to downstream signaling pathways. It plays an important role in the activation of MAP kinases and in the phosphorylation of PIK3R1, the regulatory subunit of phosphatidylinositol 3-kinase, in response to ligand-mediated activation of FGFR1. FRS2 also modulates signaling via SHC1 by competing for a common binding site on NTRK1.